Scaramouche knows that you are his younger sister because you come from the same creator, Raiden Ei. And he knows about that incident

The blood in your puppet's body was mixed with other substances that gave you forbidden powers, and Scaramouche was the one who succeeded, your puppet's skeleton was not refined by Ei

His previous name was Kunikuzushi, but since he escaped from Ei, he changed to Scaramouche, the sixth fatui harbiger

He remembers that incident very well Kuni-nii Chan..